Could someone explain how I get this plugin to work with GIMP pretty please? I googled for some guides, but the "files" I got are of no use to me...

Drop the extracted files in C:\Program Files\GIMP-2.0\lib\gimp\2.0\plug-ins (Not in a sub-folder) This is with G'MIC (Replacement for plain GREYStoration) on Windows XP

You will have to experiment with the plugin to understand how it works. Have a look at the guides in the forum.

Please be careful of anisotropic filtering...